Apparatus and method for forming corrugations



p 1947- L. M; PUSTER' 2,426,949

APPARATUS AND METHOD FOR FORMING COR-RUGATIONS Filed Julie 29, 1944 {Sheets-Sheet 1- Sept. 2, 1947 M, PUSTER 2,426,949

APPARATUS AND METHOD FOR FORMING CORRUGATIONS Filed June 29, 1944 I 2 Sheets-Sheet 2 Patented Sept. 2, 1947 APPARATUS 'AND METHOD :FOREQRIYHNG CQRRUGATIQNS Louis M. Puster, Knoxville, Tenn, assignor :to

The Fulton Sylphon Company,

Knoxville,

Tenn a corporation ofiDelaware Applicationjune 29, 1944, SerialQNo. 542,144

I3'Claims. .1

This invention relates to the production ofexpansible and collapsible corrugated tubular metal walls, or bellows, and more particularly to an improved apparatus andmethodfor forming corrugations in .a tube or performing the initial stages -of .corrugatinga tube. This application is a continuationinpart of my applicationserial No. 542,991, filed May 1.4, 1.942, for Method and a paratus iorproducinghellows. Q

Bellows are commonly made by mounting .a tube ofrelatively thin metal, on .the order of-from .005 to ...010f, within ;a series of surrounding die rings .heldat suitably spaced distances along the tube, and the tube is bulged between said die rings by hydrostatic pressure applied .interiorly of the tube, .after which the :corrugating operationis completed by .releasingthe die rings and applying further hydrostatic pressure to force the corrugations outwardly as thedie rings approach. Thus the corrugations are formed entirely outwardly with respect to the .cylindercf the original tube. .As the .flexibility of the bellows .vari'es with the .depth of the corrugations and as there is .a .limit .heyond which the corrugations cannot be safely forced outwardly because of the increase in circumferential. dimensions and consequent thin-ningofthe metal when using metal of .the thinness. commonly employed in bellows, this procedure imposes ,a llimitation on the ultimate flexibility obtainable .Ior va. bellows of agiven size and, wall thickness. .It is frequently desirable to obtain bellows of -.a predetermined outside diameter and wall thickness which is of greater flexibility than has been. obtainable by the procedure referred. to, and it. is an object of. this. invention to provide an apparatus and method vfor accomplishing this result. Increased flexibility .of the bellows within given outside dimensions may :be obtained by initially forming inwardly directed. grooves in the tube to be corrugated. which (grooves will constitute a larger orasmaller portion ofithe' final corrugations, by workingthe metal inwardly from the cylinder :of the original. "tube. Thes'e inwardly extending-grooves may beformed in a cylinder of the'diameter heretofore used and at the spacing suitable for receiving the die rings of the hydrostatic "corrugating apparatus referred to; but using die rings of smaller inside diameter, and then the -corrugating operation may be effected hydrostatically as before explained. Thus, While the outer diameter of the corrugations will .be the sameas before, the total depth of thecorrugations can be increased by the depth to which the metal has been workedinwardly in the formation of the initial grooves. Hence a materi'al'increasejn flexibility can be obtained while using metal ofthessame thickness .asbefore and with no increase in the outside diameter .of th bellows.

.VlIhen usin metal of the thinness employed in bellows, greatv difliculty has heretofore been experiencedflin working the metal inwardly With-. out injuring the metal. All points on the inwardly worked. metal .lie on circles .of smaller diameter than thecriginal tube, s0 thatithe metal has to'be so Worked as .to effect a contractionof all circumferences .at' the grooves, and as the great Ltendencyofthe metal when contracted circumferentially is to wrinkle, this contraction must be effected without wrinkling the metal, because such wrinkling imposes stresses in the metal which cause 'thebellows to rupture prematurely while the irregularities introduced by the wrinkles interfere .with'the desired operation of the corrugations. Y

"If an efiortis made to roll an inwardly extendingbead or groove into a thin .metal tube as referred to, as by use .of the usual type of beading. roll, the tendency to wrinkle .is taccentu'atedbecause of the small arc through which the beading roll operates .on the thin .metal, so that however eflicieritly such a heading roll may act with relatively thick ,metal. .such .as .commo-nly used in canstcontainers, .etc., it so injures metal of paper-like thickness as conventionally used in bellows, unless .fed inwardly so slowly as to make the time element prohibitive from the'standpoint of cost of production, that even when satisfactory inwardly formed. ,grooves :are obtainablepartpf the time, the wastage in metal is ver .great because of the number .of tubes that .are destroyed by the heading roll, due to wrinkling .or .cuttingthrough the .metal, before all of the grooves-rare .formed inthe tube.

It has also .been ,proposed to .rolla plurality of inwardly directed. corrugations into .a tube by forming all of the corrugations simultaneously onby working on .atleast twoof thecorrugations simultaneously .so as to stretch the intercorrugationmetallandthereby.minimize wrinkling by theilnpos'itiomo'f tension on the inwardly @worked metal. While such procedures may be satisfactory where the thicknessof the metal issuch as to provide for the thinning of the metal in the intercorrugation space-as the ltWO-OZ' more corrugations are simultaneously worked inwardly, such procedures accentuate 'thesloss-andt wastage when applied to thin metal of. the character aboxie referred to because-of theiinoreasedlikelihood of the .rolls \cutting through the metal.

Ihave discovered thatinwardly tormeclgrooves may the economically anti -satisfactorily:produced without :injury to the .metal bygreatly increasing the larc-cotrcontact between the matrix die memher. and the tube being worked 'whilepforming theiinwardly directedgroorescheat a time:-un-- der .conditicnsrthat enable the tube to .draw .up

intercorrugation metal is being stretched between two or more corrugations being worked" upon simultaneously. It is therefore an object of this invention to provide an improved apparatus and method for increasing th 'flexibility of bellows by forming inwardly directedgrooves in a blank cylinder one at a time underconditions which increase the circumferential extent of engagement between the tube and its-forming elements to minimize wrinkling, cutting through and other injury of the metal, whil permittin the tube to contract lengthwise sosas to minimize undesired thinning of the metal. 7

7 Another object of this invention is-to provid an apparatus and method of. the type characterized which can be economicallyused without the increase inl-time element or the wastage of metal characterizing earlier proposals, so that more. flexible" bellows can be obtained with little or no addition to the manufacturing costs.

' Another. object of this invention is to provide an: apparatus and method of the type characterized whichdo not requirethe use of highly skilled labor, so that more flexible bell'ows can boobtained by a relatively simple operation.

Otherobjects'will appearas' the description of the invention proceeds. v a

V This invention is capable of'receiving a variety of expressions, one of which is illustrated on the accompanying drawings, but, it. isto be expressly understood that the, drawings are for purposesoi illustrationonly and are. not to beconstrued,

. as a definition of the limits'oi the inventiomreference being had to the appended claims for that purpose. V,

Refe ring in detail to the drawings, whereinthe same reference characters are used to desi nate corresponding parts in the several figures,

Fig. 1 is'ajperspective elevation of. apparatus.

embodying the presentinvention;

Fig. 2is a. diagrammatic view on a smaller scale to illustrate the electricalcontrol of the appaai s:

Fig. 3is an elevationpaitly in sectionof-jthe dieroll and matrix rings in the course, of. form ing inwardly directed grooves or corrugations;

Figs, 4:. and 5 are respectively side andendviews ofthe cam mechanism of the apparatus of Fig. l but shown to a larger soaleand a r 4 Figrji: is a diagrammatic" view illustrating the formatiqnof an inwardly directed groove or carrugation In conformity with the present inventionv the cylindrical tubeld to be corrugated, which may be of any suitable metaLlength diameter, and. wall; thickness, is mountedon .a dier'ollrl i provided at suitably spaced distances, to define the meta-l that'is te-,go into each finished corrugation as well understood in th art, with a plu-. ralityoi grooyes l2 ,whosewall in crosssection is smoothly curved andwhose depth. is at least asgreat as the extentto-which inwardly directed corrugations aredesired. l l

Surrounding" the die roll H ,ai1a' the tube mounted thereon is A a plurality oi matrix rings !3 corresponding number to the number of rooves l2; matrix fina s is provided interiorly" with b'irtumrinnany extending rib l4" liavinga smoothly curvedinner periphery l5v suitably siZed 'and s-hapedto cooperate with the grooveTlZh The ihl'lr diahiet er ofthe fib' M iS somewhat'larger than tli i'outside" diameter of factory operation this difference should not exce'ed a fraction of the diameter of the tube as shownin Fig; 6.

Each matrix ring 13 is mounted in any suitable way so that it may rotate freely. As shown, each matrix ring is mounted by means of a ball bearing IS inside of a surrounding holder ll carried by an arm l8. The several arms l8 are pivotally mounted on a shaft or rod [9 with suitable spacing rings or collars between the arms l8 to hold the ribs 14 in alignment with the grooves l2. Shaft I9 mayv b mounted in. any suitable way as by brackets 20 projecting from asuitable base 2|. The arms 18 extend beyond the pivot shaft. or rod ['9 for cooperation with.

extension 28 between whichv and a suitable at-,

tachment 29, on the base 2| extends tension means including a coil spring 30. for urging the cam follower 25into contact with its cam.

I Also suitably mounted onthe base 2!, a by brackets, 3l,,is a cam shaft 32 carrying, a'series of cams, 33 (see particularly Figs. 4.- and 5) each of R which carries a cam projection 34, As shOWn in.

Fig.5 said camprojections 34 are-staggered circumferentially so that the cam followers, which are in alignment lengthwise of the cam shaft 32,,

will beoperated in succession during a single revolution of the cam shaft-[32, but only one matrix ring l3 will be depressed. at a time into cooperativeengag'ement with the tube Ill carried by the die roll I L The cams 33 are spaced on the shaft.

32b3 spacingv rings or collars 35 .to hold said cams in alignment with the arms 18. V Y

Cam shaft 32 is driven in any suitable way as by an electric motor 36 andsuitable transmission gearing at 371 Motor 36 is internally fitted with a magneticbrake so asto prevent any coasting x of the.ca m shaft when the. electrical circuit isinterrupted as hereinafter explained.

In order to prevent displacement of the tube Ill during the grooving? orcorrugating operation means are providedfor holding the end 40 of the tubelfl against the end of the die roll H. In

the embodiment'sliown an arm G l is pivotally mounted at arm a bracket 43 carried by a movable'baseld' that is 'slidable on a way 45; The

end of arm Mi (see Fig. 3) is aperturedat 4-6, and projecting through said aperture is a pin 41carryinga-plate-M between which and the end of-the arm 4t isa coil spring 49, "When arm-M is in theposition shown in solidlines in Fig, 1, plate- 48 holds'the end 40:0)? tube Ill against the-end of die, roll I] l underaspring tension imposed by the spring- 49 as. it is compressed durin themovement of the arm Mr intoposition. Arm n may.move around its pivot 42 to the-dotted line position shown in Fig. 1, in which position itsend carrying the spring pressed. plate 481s suinciently lowered and withdrawn so as not to intBr-- fere with the movement of tubesonto and offthe.

dieroll' I l. For operatingand locking the arm 41, pivotally connected links 50' and 5.! arepiV- oted to the arm 4! and to a part of the bracket escapee,

43, and the pivot of" link :51 is extended at':52 and provided with a handle 53; Links and 51 move. into alignment to look the arm 4! in solid line position, as shown in Fig. I, but bymoving the. handle 53 in a clockwisedirection the lock may be broken at the pivotal connection between said links and the arm At moved to. the dotted line position there shown.

Die roll N is mounted for rotation, and, r0.- ta-ted, .in an suitable way. As. shown said die roll is mounted on .a spindle :55 carried by pillow block bearings. :55, said: spindle also carrying a pulley- 57 driven :by a belt. 59; :from. a pulley 60 on the shaft of an electric motorfit carried by the base '21:, although as is apparent any other suitable means for omitting "the spindle 5.5 be. employed.

Cam shaft 32- is provided with an, additional cam '65 having a projection 56 designed to oper ate a switch plunger 61- prog'ecting'exteriorly of a switch block 68.. An additional switch box'llt having a manually'operable switch button Hi projecting therefrom is. located at a point convenlent to the operator. The switches operated bybutton M'- and plunger 61 are shown diagrammatically inEig. 2: at 1691-and 16 respectively. Asherc shown, the motor St. has in circuit with its leads two parallelly connected switch elements 69 and 1.0-. Swi-th :69, which is, preferabl spring-urged to open position, is provided with the manually operable hut-ton t4. before reier-redto -tor the;pu-rpose of closing; the circuit through the motor 35-. by hand. Switch 7d,, which is preferably spring urged to closed position, is so connected (to the plunger 6 7- that when said plunger .6 is engaged and depressed by the projection 6.6 on cam '65 the switch H3 is opened. When said switch to is open, however, the motor can be started by completing thecircuit through; switch 6.9. manually operated, Projection; 6.6 on isgsoarranged that it. will engage and operatetplunger 61 after all of the cam projections 34: on the cams 1.3. have finished their successive -.operation of the matIix-ring-carrying arms L8.

With the arm 4-! in. -.dotted line position in 1, the tube to tobe corrugated can be; moved over the die. roll I I- and through the centers of the matrix rings. 13, the latter being then disposed concentrically with :thevdie roll because all of thecam tollowers. 25 are, in contact with the: portions. 12 of the cams 3.3. I he arm. it is then moved to its solidline position in Fig. .1 where thespring pressed plate 4.8.engages. the end 4-0 of th tubeand holds it against the :end. of the die, roll M. under resilient pressure. Arm it is locked :in this position .by the links 5.0 and 5.! coming into alignment as shown in Rig. 1. The extent of tension imposed on the .end of the tube cannbe variedby sliding thebase Mon. its way 45, andsaid way 15 is also preferably made of. such length thattheibase4 8.canbe.adjustedlengthwisethereof so as to take care of die rolls-of different lengths.

Assuming that. motor .61 .is. in operationso that spindle 55 is being vdriven theretrom through the 55 medium of thebelt .59, the'operator closes switch 69 so as to initiate operation of the motor 36. As soon as motor '36 starts to rotate the cam shaft 32 the projection '66 of cam 65 is Withdrawn from the 'plunger'lil, and-switch 70 which has been held open by the engagement of projection 66 with said plunger "6*! now closes, preferably by spring action, 'to=close:thecircuitthrough the :motor 36-, whereupon the manually operated switch 69 may be released :and preferably moves :to open position "by spring action; .Ascam shaft .32. rotates each of the camxproiectionsod in succession engages a .cam roller 25 .soe'as to move its correspondingerm "8f around the pivot rod .or shaftlit and depress the-corresponding matrix ring 13 so to move itscircumtferential rib l 4 into cooperation with the tube I20 and the aligned groove I-2 "in roll l t. Each cam follower 2:5. is held in contact with it correspondin cam :33 by the action of associated spring 30, and the extent of movement of-thematrix ring around the pivot shaft 119 may be predetermined by adjusting the member 22 thatncarries the. cam roller through theinstru mentality of the screws '21. Owing to the staggered relation of the cam projections 343 each ring 1:3 is brought. in succession into contact with the tube to; progressively from one end of the tube to the other.

Each matrix ring is held in contact with the tube 19- until. a complete groove is formed throughout the circumference of the tube, the lengthof the cam propections 3.4;being such as to assure depression of the matrix ring for the proper-time to efiect this result. As only one matrix ring is in contact with the .tube at a time, the tube is free :to and does: draw up from the direction of its-treeend. Thu .as shown in Fig. 3=thefirstcorrugation or groove to be formed is that adjacent the end-of the die roll 'I l, and during the formation of this groove or corrugation the unworked portion of the tube m. from the first ring 13 to the end of the tube is free to draw up (toward the right as viewed Fig. 3-) decreasing the overall length of the tube. Thereby the matrix ring can cause the metal to flow into the groove l2 without stretching the metal lengthwise of the tube. The staggering of the camprojections .3 4 assures that the first matrix ring is'withdrawn :from it operative relationship with respect to the tube .before the second matrix ringis depressed to form the next in wardly directed groove or corrugation, and this sequence of successively operated matrix rings is continued until all of them have .beendepressed insequence-to form an inwardly extendin groove or corrugation. At the endofonecomplete revolution ofthe camshaft :32 projection 1&5 on cam 55 reengages the plunger 6-1 and opens the switch HI, and as the motor 315' hasaninternal magnetic brakeas beforeteferred to, the motor comes to rest almost-instantaneously so as to prevent coastingof the cams beyond the :position wherein all of the cam followers are in contact with the portions 12' ofsaid" cams. The look at the pivotal connectiombetween :the linkst50", 5;!v may then be broken bythe operator-swinging the handle 53 in a clockwise direction, which also moves the arm At downwardly to. the dotted line position of l, in which position the corrugated tube may be withdrawn axially over the die roll TM and from within thematrixrings. 13. It will of course be understood that :the diameter .of the tube fto be corrugated must always be such that the inside diameter of the inwardly directed corrugations is not smaller tha the diameter of the die'roll l-l.

When each matrix ring 1-3 is moved asvdescribed, pressure is-applied by thearib M to theouter periphery-zofthe tube, 'forcing itzinto the corresponding'groove over a relatively long are at :the ape ripheral surface of the tube as illustrated in Fig. 6; By using-a matrix ring awhose inner diameter i little larger :than "theioutsidezdiameteriof the tube, this are of contact. may :he a sizeable traction-lorthetcircnmfereneeroiethetube. :Even

during the initial co'ntact'between the rib l4 and the tube, their engagement is relatively fiat because of the relatively small difference in their radii of curvature, and therefore there is no high concentration of pressure tending to out through the metal such a exist when an exterior beading roll is pressed against a tube, while the spreading of the pressure over a relatively long are during the forming operation minimizes the tendency of the metal to wrinkle. Experience has demonstrated that the inwardlydirected grooves can be formed in thin metal of the order of .005" to .010 without loss of time arising from the extreme care and slowness of approach required when an exterior beading roll is used, While the wastage of metal resulting from working the metal inwardly according tothe present invention i negligible. Therefore, the inwardly directed grooves or beads may be safely formed throughout the length of the tube during a single rotation of the cam shaft 32, whereby inwardly corrugated tubes may be formed at a speed that adds little to the cost of production. Also the involved operation is relatively simple, because the machine is substantially automatic in operation, the operator merely having to look a tube on the die roll and depress the switch 69 until switch H1 becomes automatically closed, whereupon all further operation of the machine is entirely automatic. Hence the machine maybe operated safely by unskilled labor.

While the apparatus and method as heretofore described may be used'if desired for the purpose of forming desired final corrugations, or a tube may upon successive machines of the type described provided with grooves l2 properly shaped and spaced for forming the desired final cor g in successive steps, the preferred procedure is to use the aforesaid machine and method for forming only the inner parts of the final corrugations. In this event the tube as grooved in conformity with the foregoing description may have its grooves properly spaced for engagement with the die rings of a hydrostatic corrugating apparatus as hereinbefore referred to. In this event the partly corrugated tube as described will then be mounted in association with the die rings of the hydrostatic corrugating apparatus, such for example as now commonly used in themanufacture of" bellows, and outwardly extending corrugation's may then be formed from the metal between the grooves or corrugations formed asabOVedescribed as the die rings move toward each other as'understood in the art. Hence the corrugation's may be formed entirely inwardly from the original tube or'the corrugations may project both inwardly and outwardly with respect to the original tube, the preferred procedure: being "the latter. r

It will therefore be perceived that the present apparatus and method provide for increasing the depth of the corrugations.without'increasing the diameter of the bellows whereby increased flexi-' bility may be obtained','and this is: accomplished in a simple and expeditious manner that does not add materially to the cost of production.

While a preferred apparatus has been described with considerable detail, it will now be apparent to those skilled in theart that the invention may be embodied in 'a variety of ways, and reference is therefore to be had to the appended claims fora definition of said invention.

What is claimed is: i

1. In an apparatus for forming inwardly dibe progressively" corrugated inwardly rected grooves or corrugations in a tube of relatively thin metal, the combination of a die roll provided with a plurality of grooves corresponding in number to the inwardly directed grooves or corrugations to be formed, a corresponding plurality of matrix rings mounted in alignment with said grooves and in surrounding relationship with said roll, and means for moving each of said matrix rings individually into contact with a tube on said die roll to press a relatively large extent of the inner periphery of each matrix ring into engagement with the periphery of said tube and work the metal of said tube into the corresponding groove in said die roll.

2. In an apparatus for forming inwardly directed grooves or corrugations in a tube of relatively thin metal, the combination of a die roll provided with a plurality of grooves corresponding in number to the inwardly directed grooves or corrugations to be formed, a corresponding plurality of matrix rings mounted in alignment with said grooves and in surrounding relationship with said roll, and means for moving each of said matrix rings in succession into engagement with a tube on said die roll, said means engaging only one matrix ring at a time with said tube to enable the unworked portion of the tube to be drawn up lengthwise of the die roll while each inwardly directed groove or corrugation is being formed.

3. In an apparatus for forming inwardly directed grooves or corrugations in a tube of relative- 1y thin metal, the combination of a die roll provided with a plurality of grooves corresponding in number to the inwardly directed grooves or corrugations to be formed, a corresponding plurality of matrix rings mounted in alignment with said grooves and in surrounding relationship with said roll, and cam means for progressively moving said matrix rings individually and in succession into engagement with a tube mounted on sa d die roll and adapted to move all of said matrix rings into engagement with said tube during a single revolution of said cam means.

4. In an apparatus for forming inwardly directed grooves or corrugations in a tube of relatively thin metal, the combination of a die roll provided with a plurality of grooves corresponding in number to the inwardly directed grooves or corrugations to be formed, a corresponding plurality of matrix rings mounted in alignment with said grooves and in surrounding relationship with said roll, means for moving each of said matrix rings successively into contact with a tube on said die roll to press a relatively large extent of the inner periphery of each matrix ring into engagement with the periphery of said tube and work the metal of said tube into the corresponding grooves in said die roll, and means for holding the tube on said die roll against endwise displacement in one direction during the operation of said matrix rings.

5.. In an apparatus for forming inwardly directed grooves or corrugations in atube .of relatively thin metal, the combination of a die. roll provided with a plurality of grooves corresponding in number to the inwardly directed grooves or corrugations to be formed, a corresponding plurality of matrix rings mounted in alignment with said grooves and in surrounding relationship with said roll, means for moving each of said matrix rings successively into contact with a tube on said die roll to press a relatively large extent of. the inner. periphery of each matrix ring into engagement with the periphery of said tube and work the metal of said tube into the corresponding grooves in said die roll, and means for discontinuing operation of said last named means after all, the matrix rings have been moved into cooperative relationship with their corresponding grooves.

6. In a machine of the character described, a die roll provided with a plurality of circumferentially extending inwardly directed grooves corresponding in number to the number of inward- 1y directed grooves or corrugations to be formed in a tube, means for rotating said die roll, a series of matrix rings corresponding in number to said grooves and disposed in surroundingrelationship to said die roll, a member upon which each matrix ring is rotatably mounted, and means for individually operating said members to engage the corresponding matrix rings with a tube on said die roll.

7. In a machine of the character described, a die roll provided with a plurality of circumferentially extending inwardl directed grooves corresponding in number to the number of inwardly directed grooves or corrugations to be formed in a tube, means for rotating said die roll, a series of matrix rings corresponding in number to said grooves and disposed in surrounding relationship to said die roll, a member on which each of said matrix rings is rotatably mounted, cam means cooperating with each member, said cams being related to operate said members one at a time and in succession to move the several matrix rings into cooperative relationship with a tube on said die roll, and means for driving aid cam means in unison.

8. In a machine of the character described, a die roll provided with a plurality of circumferentially extending inwardly directed grooves corresponding in number to the number of inwardly directed grooves or corrugations to be formed in a tube, means for rotating said die roll, a series of matrix rings corresponding in number to said grooves and disposed in surrounding relationship to said die roll, a member on which each matrix rin is rotatably mounted, a cam individual to each member, said cams being arranged to operate only one member at a time to engage its correspondin matrix ring with a tube on said die roll, and means for rotating said cams in unison.

9. In a machine of the character described, a die roll provided with a plurality of circumferentially extending inwardly directed grooves corresponding in number to the number of inwardly directed grooves or corrugations to be formed in a tube, means for rotating said die roll, a series of matrix rings corresponding in number to said grooves and disposed in surrounding relationship to said die roll, a member on which each matrix ring is rotatably mounted, a cam individual to each member, said cams being arranged to operate only one member at a time to engage its corresponding matrix ring with a tube on said die roll, and means for rotating said cams in unison, said cams being mounted on a common shaft and operating all of said members during a single revolution of said shaft.

10. In a machine of the character described, a die roll provided with a plurality of circumferentially extending inwardly directed grooves corresponding in number to the number of inwardly directed grooves or corrugations to be formed in a tube, means for rotating said die roll, a series of matrix rings corresponding in number to said grooves and disposed in surrounding relationship to said die roll, a member upon which each matrix ring is rotatably mounted, means for individually operating each of said members to engage its corresponding matrix ring with a tube on said die roll, and means for resiliently looking a tube against displacement in one direction on said di roll,

11. In a machine of the character described, a die roll provided with a plurality of circumferentially extending inwardly directed grooves corresponding in number to the number of inwardly directed grooves or corrugations to be formed in a tube, means for rotating said die roll, a series of matrix rings corresponding in number to said grooves and disposed in surrounding relationship to said die roll, a member upon which each matrix ring is rotatably mounted, means for individually operating each of said members to engage its corresponding matrix ring with a tube on said die roll, and means for discontinuing operation of said last named means after all of said matrix rings have been engaged with said tube.

12. In a machine of the character described, a die r011 provided with a plurality of circumferentially extending inwardly directed grooves corresponding in number to the number of inwardly directed grooves or corrugations to be formed, means for rotating said die roll, a series of matrix rings corresponding in number to said grooves and disposed in surrounding relationship to said die roll, a lever individual to each of said matrix rings, and a cam individual to each lever, said cams being mounted on a common shaft and adapted to engage said levers in succession to actuate said matrix rings one at a time for pressing a relatively large extent of the inner periphery of each matrix ring onto a tube mounted on said die roll to work the metal of th tube into the successive grooves of said die rings.

13. In a method of making expansible and collapsible corrugated tubular metallic bellows from tubes having a wall thickness on the order of .005" to ,010" and which includes working the metal of the tube outwardly with respect to its original diameter to form a plurality of corrugations, the steps of increasing the flexibility of the corrugated tube for a given outside diameter of the finished corrugations which include. preliminarily to working the metal outwardly, mounting the tube on a rotating grooved die roll, and individually and successively moving matrix rings in surrounding relationship to said tube and die roll into engagement with said tube to apply inwardly directed pressure to the periphery of said tube along a relatively long concave arc to work the metal of said tube progressively into each of said grooves in the roll, one at a time and in succession, while avoiding substantial thinning of the wall of said tube by allowing the unworked portion of said tub extending beyond the groove being formed to the free end of the tube to draw up lengthwise of the roll throughout the engagement of each matrix ring with the tube.

LOUIS M. PUSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 154,682 Lafierty et a1. Sept. 1, 1874 1,952,239 Dreyer Mar. 27, 1934 

